Describe two different ways that histone modifications may alter chromatin structure.

Transcriptional regulation relies on chromatin modifications that affect the physical state of chromatin and the accessibility of genomic DNA to RNA polymerase. This is commonly referred to as epigenetic regulation of gene expression, and it is highly dynamic. Epigenetic modifications vary from cell to cell and vary over time and in response to different environmental conditions within the same cell. Fill in the table below based on your knowledge of the impact of different epigenetic modifications on chromatin structure and transcription.   Chromatin/DNA Modification Protein Responsible Effect on Chromatin Effect on Transcription of Associated Genes Histone Acetylation ? ? ? ? HDAC ? ? Histone Demethylation ? ? ? ? HMT ? ? DNA Methylation ? ? ?

Describe how methylation and acetylation of the histones changes gene expression in eukaryotes. What groups are added? How do these processes physically affect chromatin structure? Silencing or Enhancing expression?

Possible genetic modifications that can cause epigenetic changes in gene expression include: A- all answers are correct B- histone acetylation C- chromatin remodeling D- histone variant localization  e- DNA methylation

The diagram below shows the structure of DNA from the level of a gene to a condensed mitotic chromosome. At each of the four locations marked, indicate how a gene may be regulated by selecting from the choices given.  Some answer choices may fit into more than one position; however, you should use each answer choice only once.   Choices given: Alternative splicing within the gene sequence can lead to different forms of mRNA. A promoter region can be blocked by another protein. Histone deacetylation can prevent DNA from unwinding. A regulatory region can be bound and increase transcription rates.

What is the result when the core histones are acetylated via histone acetyltransferase? A) The result depends on which histone is modified. B) The DNA becomes more tightly associated with the core. O C) The DNA becomes less associated with the core. This modification has no effect on how tightly associated DNA will become with the core.

The following image shows the 'beads-on-a-string' model of DNA and the effects of histone modification on chromatin structure. What effect does histone acetylation have on Gene 1? Gene 1 De-acetylation Acetylation Ac Ac Gene 1 Ac Ac Ac O Acetylation increases expression of Gene 1 O Acetylation decreases expression of Gene 1 O Acetylation causes a mutation in Gene 1 O There is no way to tell from this figure

Define both transcription and translation. In addition, describe the role(s) of each of the following in the processes of gene expression and protein synthesis:  DNA, mRNA, tRNA, rRNA, ribosome(s), RNA polymerase, codon, anticodon, amino acid(s) and polypeptide(s). Be detailed in your answer.

Which is the expected outcome following the deacetylation of histones? a) Coiling of chromatin, preventing it from being accessed by transcriptional machinery b) Coiling of chromatin, allowing it to be accessed by transcriptional machinery c) Uncoiling of chromatin, preventing it from being accessed by transcriptional machinery d) Uncoiling of chromatin, allowing it to be accessed by transcriptional machinery

Base on your knowledge of DNA, chromosomes and epigenetics and upon examining the picture below, name two epigenetic factors and at least one non-epigenetic factor present on this picture. [HINT: which of the factors shown on the picture do you expect to change based on the interactions with an environment and which you expect unchanged?] Methyl Group DNA Chromatin Epigenetic Factor Histone Histone Tails Chromosome